Popular Democratic President Andrew Shepherd is preparing to run for re-election. The President and his staff, led by Chief of Staff and best friend A.J. MacInerney, attempt to consolidate the administration's 63% approval rating by passing a moderate crime control bill. However, support for the bill in both parties is tepid: conservatives do not want it, and liberals think it is too weak. If it passes, however, Shepherd's re-election is presumed by his staff to be a shoo-in, and Shepherd resolves to announce the bill, and the Congressional support to pass it, by the State of the Union.

With the President of France about to arrive in the United States to attend a state dinner in his honor, Shepherd—widowed when his wife died of cancer three years earlier—is placed in an awkward predicament when his cousin Judith, with whom he had planned to attend the dinner, gets sick.

The President's attention soon focuses on Sydney Ellen Wade, just hired by an environmental lobbying firm to persuade the President to pass legislation committing his Administration to substantially reduce carbon dioxide emissions. During their first meeting, Shepherd and Wade are immediately intrigued by each other. At this meeting, Shepherd strikes a deal with Wade: if she can secure 24 votes for the environmental bill by the date of the State of the Union, he will deliver the last 10 votes. Whatever his personal feelings toward Wade, he expresses this to his staff, especially the pragmatic A.J., as a sound political move. He believes Wade will not be able to get enough votes to meet her side of the deal, thus releasing Shepherd from responsibility if the bill fails to pass.

Later that evening, in a series of phone calls, Shepherd invites Wade to the state dinner. During the State dinner and subsequent occasions, the couple fall in love. When the Republican presidential hopeful Senator Bob Rumson learns "the President's got a girlfriend," he steps up his attacks on Shepherd and Wade, focusing on Wade's activist past and maligning Shepherd's ethics and his family values. The President refuses to respond to these attacks, which drives his approval ratings lower and costs him crucial political support, without which his crime bill seems doomed to failure.

At the White House Christmas Party, Wade is dejected about her meeting that day with three Congressmen from Michigan about the environmental bill and how it was a dismal failure; in the process, she inadvertently mentions to the President and A.J. that the Congressmen in question said the only bill they were more interested in defeating than the President's crime bill was Wade's environmental bill. Shepherd and A.J. are conflicted by this information as Wade clearly had no idea of the implications of this casual conversation, much less that they might actually use this information in their favor and against her environmental bill.

Eventually, Wade does manage to get enough votes to meet her part of the deal. However, in the meantime, Shepherd's team discovers he is exactly three votes short, with no other apparent options to acquire them except by shelving the environmental bill, thus solidifying the support of the three Congressmen from Michigan—which he agrees to do. This results in disaster for Wade as she is immediately fired from her lobbyist job for failing to achieve her objectives, as well as seemingly jeopardizing her political reputation. She visits the White House to break up with Shepherd and says that she has a job possibility in Hartford, Connecticut. He tells her politics is making choices, his number-one has always been the crime control bill, and that he does not want to lose her over this. She congratulates him on getting the leverage to pass a crime bill that in no way will help fight crime. She concludes, "Mr. President, you have bigger problems than losing me—you've just lost my vote."

On the morning that he is to deliver his State of the Union Address, and after an argument with A.J., Shepherd makes a surprise appearance in the White House press room and rebuts Rumson's attacks on Wade's past and his own values and character. He declares he will send the controversial environmental bill to Congress with a massive 20% cut in fossil fuels — far more than the 10% originally envisioned — and that he is withdrawing his support for the weak crime bill, promising to write a stronger one in due time. In his speech he even promises gun control, in an attempt at root-and-branch solving of America's problems. His passionate and erudite defense of those things in which he believes, in contrast to his earlier passive behavior, galvanizes the press and his staff.

Shepherd declares he is "going over to her house and I'm not leaving until I get her back", but Wade enters the Oval Office before he can leave. The couple are reconciled and the President, accompanied by Wade, leaves to give his State of the Union Address. The film ends with Shepherd entering the House chamber to thunderous applause.

Originally, actor Robert Redford approached a number of screenwriters with the single-line premise, "the president elopes." Sorkin, on the basis of his treatment, was selected by Redford to write the screenplay with the expectation that Redford would star. When Reiner was brought aboard to direct, however, Redford dropped out. At the time, his publicist attributed Redford's decision to his desire "to do a love story, but (Reiner) wanted to do something that was ultimately about politics." Other sources suggested that Redford and Reiner "didn't get along,...It was a personality thing."[8]

Upon its theatrical release, The American President proved to be successful at the box office with a worldwide gross of $107.9 million on a budget of $62 million.[2] In the years following its release, it has remained a favorite on cable television and home video.[citation needed]

The film was a critical success. It received praise and "Two Thumbs Up" from Siskel and Ebert who were surprised by how good the film was considering Rob Reiner's previous film, North, was both of their selections for the worst movie of the year. Ebert said after detesting North he was very happy and pleased to give Reiner's next film a unanimously positive review. Siskel praised Douglas and Bening for their performances;[10] he did, however, disapprove of Janet Hirshenson and Jane Jenkins' decision to cast Douglas and Sheen in the same film and especially in similar roles within that film, expressing the worry that the similarity between the two actors' appearances would lead audiences to confuse their respective characters. According to Rotten Tomatoes, 90% of critics gave the film a positive review, with an average rating of 7/10.[11]

The screenplay, which writer Aaron Sorkin told TV Guide he wrote while often high on crack cocaine,[12] inspired many aspects of his television drama The West Wing. The two productions follow the staff of a largely idealized White House, and like many of Sorkin's projects, share ideologies. Even the set of the Oval Office in The American President was later used in The West Wing.

The film's influence can be seen most clearly in early episodes of the series; some dialogue in the two are nearly identical. Sorkin has been known to say that much of the first season was actually taken from material he edited out of the first draft of The American President's script.

One of the issues touched on in the film and developed in the series relates to gun control bills, developed in "Five Votes Down". While the bill is ultimately withdrawn by President Shepherd because it is ineffectual, on the series President Bartlet and his staff work hard to pass their bill even though it is badly flawed (and end up doubly unhappy when VP John Hoynes, whom the President and senior staff are feuding with, clinches the bill for them by persuading an influential southern Democrat to support it).

More significant is the issue of a "proportional response" to military attacks on American assets abroad. In The American President, Andrew Shepherd finds himself in the Situation Room having to order such an attack against Libya's intelligence headquarters after they bombed a missile defense system called "C-STAD" (Capricorn Surface-to-Air Defense) which had been positioned by the U.S. in Israel. He muses for a single line "Someday, someone's gonna have to explain to me the virtue of a proportional response", before giving the order. In "A Proportional Response", President Bartlet finds himself in similar circumstances (Syrian intelligence shot down a U.S. plane in Jordan and killed numerous Americans, including a young Naval officer who the President had decided would be his personal physician) and, seated in the White House Situation Room with his own National Security Council asks: "What is the virtue of a proportional response?" In both cases, the President chooses a military response that is relatively measured, but in the movie President Shepherd never considers a "disproportionate" response while President Bartlet plans such an action to destroy a large civilian airport in Syria; he eventually gives the green light for a strike similar to the one used in the movie.

The Global Defense Council, the fictional environmental lobby where Sydney Wade worked, is also featured in the West Wing episode called "The Drop-In", and is often referred to in other episodes.

In The American President, Sydney Ellen Wade is ultimately fired from her lobbyist position because the president has brokered a deal that causes her legislative effort to fail. Similarly, in the final episode of the third season of The West Wing, Deputy Chief of Staff Josh Lyman uses the same tactic and ends up getting Amy Gardner fired from her position at the Women's Leadership Conference. Josh and Amy are dating when this takes place, just as the main characters are here. However, on the TV series it is Amy who tries to scuttle a bill (welfare reform) and Josh refuses to accept the demands of three Florida GOP Congressmen because they amount to blackmail. His deal cannot be classified as a betrayal of Amy in the way President Shepherd's was of Sydney Wade.

The American President includes mention of a Governor Stackhouse, while there is a Minnesota senator Howard Stackhouse (George Coe) in the two West Wing episodes "The Stackhouse Filibuster" and "The Red Mass". In the same way, the French President attending a state dinner in The American President seems to be the same President d'Astier that is often referred to in the West Wing.

In April 2013, New York Times columnist Maureen Dowd drew a sharp contrast between President Obama's unsuccessful effort to secure passage of expanded background-check legislation in the Senate, on one hand, and the all-out vote-gathering effort in The American President.[14] The President responded to the column at the 2013 White House Correspondents' Dinner, noting the criticism and posing a series of rhetorical questions to Michael Douglas, who he said was in the audience, including, "Could it be that you were an actor in an Aaron Sorkin liberal fantasy?"[15]

In the 2016 Presidential election candidate Ted Cruz paraphrased a portion of The American President when fellow candidate, Donald Trump insulted Cruz's wife. Cruz stated, "...and if Donald wants to get into a character fight, he’s better off sticking with me because Heidi is way out of his league,” referencing the speech President Shepherd made about the attacks on Sydney Ellen Wade.[16]